Polyglycidyl ethers based on 2,2-diphenylolpropane (DPP), also known as 2,2-bis(4-hydroxyphenyl)propane, are well known commercial products. These polyglycidyl ethers, or epoxy resins as they are commonly known, are used on a large scale as the main resinous components in curable or thermosetting compositions, as may be seen from reference to "Handbook of Epoxy Resins", Lee and Neville, McGraw-Hill, New York (1967) and "Uses of Epoxy Resins", Potter, Butterworths, London 1975. These epoxy resins are compounds of general formula: ##STR1## wherein m is a number having an average value from 0 to 12.
A proportion of the glycidyl groups in the above formula may have been replaced by glycol groups, due to the methods of preparation. Compounds of formula I, wherein m is 0-1 are liquid or semi-liquid at room temperature, whereas those wherein m is at least 2 are solids at room temperature.
The glycidyl ethers of DPP have low compatibility with aliphatic hydrocarbons (which are attractive as cheap solvents), and have to be dissolved or diluted with more expensive, polar, solvents, such as ketones or glycol ethers or -esters.
For some purposes, relatively flexible cured products are required. These can be provided by incorporation-reactive flexibilizers, flexibilizing epoxides, and/or flexibilizing curing agents in the products before cure. Apart from price considerations (flexibilizing additives are usually expensive) there is generally a reduction in other useful properties, such as resistance to heat, solvents and/or chemicals.
Liquid epoxy resins based on DPP have the disadvantage that in undiluted form they have relatively high viscosity (commonly of the order of 10 Pa.s or greater at 25.degree. C.). If a resin of lower viscosity is required, the DPP-based resin is diluted with a small proportion of a reactive diluent in the form of a mono- or di-epoxide of low viscosity, such as a glycidyl ether of a monohydric alcohol or a glycol. The inclusion of such reactive diluents tends to impart reduced heat, solvent and/or chemical resistance in the eventual cured products.
U.S. patent application Ser. No. 273,704, filed June 15, 1981, discloses a class of polyglycidyl ethers prepared from a mixture of isomers of 1,1-diphenylol heptane, which are usefully compatible with aliphatic solvents, able to be cured with known epoxy resin curing agents and suitable for use as base materials for the preparation of anionic or cationic aqueous thermosetting paint binders. The low molecular weight polyglycidyl ethers based on the 1,1-diphenylol heptane isomers exhibit low viscosity.